Sweeping machines



May 12, 1970 Filed May 21, 1968 FIG. 2

C. E. ROSLUND SWEEPING MACHINES '3 Sheets-Sheet 2 INVENTOR'.

CLAE-S EMU. ROSLUN D by 64M, Su a Quad Cid/5mm May 12, 1970 c, E. ROSLUND SWEEPING MACHINES 3 Sheets-Sheet 3 Filed May 21, 1968 IN V ENT'OR CLAE-S EM. ROSLUND y cl ya gnu-only;

United States Patent SWEEPING MACHINES Claes Emil Roslund, Lund, Sweden, assignor to Asbrink Eiker Atkiebolag Filed May 21, 1968, Ser. No. 730,707 Claims priority, application Sweden, May 26, 1967, 7,411/67 Int. Cl. E01h 1/02 US. Cl. 15-82 5 Claims ABSTRACT OF THE DISCLOSURE A sweeping machine has a cylindrical brush mounted in a support assembly on a vehicle. The support assembly is vertically .adjustable by means of hydraulic jack means. In order to obtain a constant brush pressure the hydraulic jack has a double-ended cylinder and a differential pressure piston and the ends of the hydraulic cylinder are connected to a hydraulic fluid line in which the hydraulic pressure is kept constant by means of pressure control valve means.

This invention relates to a sweeping machine.

In sweeping machines comprising a vertically adjustable support assembly for a cylindrical brush rotatably mounted therein, and power means disposed between the support assembly and a stationary abutment for partially balancing the weight of the support assembly and the cylindrical brush, it is customary at present to provide the power means in the form of a spring mechanism with one it more coil springs of adjustable tension in order that the balancing force may be adjusted according to the weight of the cylindrical brush, which continuously becomes smaller as the brush is worn. The operators of such sweeping machines, however, mostly are not very thorough in making this adjustment, and inspection has shown that the sweeping machines are generally run with too high a brush pressure, which leads to unnecessary power losses and unreasonable wear of the brush. Besides, it rather often happens that the motors of sweeping machines with hydraulically operated brushes break down as a result of the hydraulic motor being overloaded through incorrect adjustment of the spring mechanism. For the practical use of sweeping machines of the type outlined in the foregoing it would be desirable for the balancing force to automatically adapt itself to the weight of the cylindrical brush as the brush is worn, but to provide in power means comprising a spring mechanism such an automatic change of the balancing force would require rather complicated means. Another disadvantage associated with the power means comprising a spring mechanism is that the flexibility of the cylindrical brush in respect of irregularities of the swept surface is not entirely satisfactory inasmuch as the brush is easily brought to oscillate when passing over such irregularities.

With a view to attaining a more satisfactory partial balancing of the weight of the support assembly and the cylindrical brush, thereby making it possible to obtain by simple mechanical means an automatic adaptation of the balancing force corresponding to the prevailing weight of the support assembly and the cylindrical brush as the latter is worn, and also permitting a hitherto unattainable great flexibility of the cylindrical brush when sweeping irregular surfaces, it is suggested according to the present invention to have as power means in a sweeping machine of the kind referred to a hydraulic cylinder in. which is movable a balancing piston having opposed differential pressure surfaces, and to connect the hydraulic cylinder on opposite sides of the balancing piston to a line for supplying hydraulic liquid at a pressure predetermined by an overflow valve. The cylindrical brush thus balanced ice quickly and distinctly follows prevailing irregularities of the swept surface and is always kept under a constant pressure which can easily be given a characteristic adapted to the wear of the brush, with the use of simple mechanical systems.

For greater clarity, the invention is more fully described in the following with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic side view of the rear part of a vehicle having mounted thereon a sweeping machine including a balancing device according to the invention;

FIG. 2 is an axial section of the hydraulic cylinder of the balancing device;

FIG. 3 is a diagram of the hydraulic system in the balancing device.

As shown in FIG. 1 a sweeping machine is mounted on the rear part of a vehicle '10, in the present instant illustrated as a jeep. Said sweeping machine comprises a pair of rearwardly extending supporting arms 11 which are pivoted on either side of the vehicle in pivot points 12 on a framework 13 rigidly connected to the vehicle so that the said arms can swing vertically about an axis transverse to the vehicle. The supporting arms 11 are interconnected at their outer ends by a cross member 14 which is provided with a pair of downwardly directed arms 15 in which .a cylindrical brush 16 is mounted for rotation. The brush is driven by a hydraulic motor at either or each mounting arm 15. The brush 16 and means for driving and mounting it are not shown in detail as said brush and said means can be of conventional design. Rigidly mounted on either or each supporting arm 11 is an obliquely forwardly and upwardly directed arm 17, and a hydraulic cylinder 20 which is arranged as a link and is of the form shown more in detail in FIG. 2 is mounted between a pivot point 18 at the upper free end of said arm 17 and a pivot point 19 on the framework 13, said cylinder 20 being connected in a hydraulic system which is also in communicationwith the hydraulic motor or motors for the cylindrical brush, as will appear from FIG. 3.

On one end wall 20a the hydraulic cylinder 20' has a lug 21 by which the cylinder is connected to the pivot point 19. Movable in the cylinder 20 is a first piston 22 which will be termed balancing piston and which has a piston rod rigidly connected thereto and extending out of the outer cylinder end wall 20b (screwed as a cap onto the cylinder), said piston rod being mounted by means of a lug 24 at pivot point 18. A seal 25 is arranged in the end wall 20b about the piston rod in the conventional manner. Movable in the cylinder between the balancing piston 22 and the end wall 20a is a floating piston 26 with projecting short studs 27 on opposite faces for abutting engagement with the end wall 20a of the cylinder and with the balancing piston 22. The floating piston 26 is provided with a sealing O-ring 28, which is not, however, the case with the balancing piston 22. No sealing piston ring is required for this piston because its opposite sides are interconnected by way of an opening 29 in the piston. At the end of the cylinder 20 from which the piston rod 23 extends there is a connection 30' for supplying and discharging pressure medium respectively to and from the two cylinder chambers on either side of the balancing piston 22 which chambers are designated 201 and 202, mutually communicate through the opening 29 and are defined by the end wall 20b and the balancing piston 22 in the case of chamber 201, and by the floating piston 26 and the balancing piston 22 in the case of chamber 202. A second connection 31 is provided for supplying and discharging pressure medium respectively to and from the cylinder chamber 203 defined between the piston 26 and the end wall 20a.

The hydraulic system illustrated in FIG. 3, in which the cylinder 20 is connected, comprises a pump 32 which sucks hydraulic oil from a tank 33 and can be driven by the drive motor of the vehicle 10. Via a pressure line 34 the pump delivers oil under pressure to a valve 35 and to a valve 36. These two valves are shown in normal position and are individually adjustable from said normal position into two different positions 35a, 35b and 36a, 3611, respectively. They are connected to a line 37 which leads to the tank 33 and contains a filter 38. In the normal position of the two valves the passage for the oil under pressure is closed at these valves, and the pump then urges the oil under pressure through an overflow valve 39 which is connected to the pressure line 34. The overflow valve 39 is adjusted for a suitable maximum pressure in the hydraulic system and is also connected to the line 37 for returning the hydraulic oil to the tank 33.

The valve 35 is adapted to control the operation of the hydraulic motor driving the cylindrical brush 16 and diagrammatically shown at 40 in FIG. 3. In position 35a of the valve the motor 40 is driven in one direction while it is driven in the opposite direction in position 35b of the valve because the connections to lines 34 and 37 are reversed in that case in the valve 35.

The remaining part of the hydraulic system has been developed only for operation of the cylinder 20 in the manner specific to the invention. Non-return valves 41a and 41b are connected to both sides of the motor 40 and permit oil under pressure, supplied to that side of the hydraulic motor 40 which temporarily is the pressure side, to flow to a line 42 through a constant flow valve 43 which restricts the flow through the line 42 to e.g. of the total flow from the pump 32. The line 42 is in communication with the connection 30 and with the valve 36 where, however, further communication is interrupted when the valve 36 is in the normal position shown, and finally with the line 37 via an overflow valve 44. The connection 31 of the cylinder 20 is in communication with a line 45 which leads to the valve 36, but for this line also further communication is interrupted when the valve 36 is in the normal position shown. If it is assumed for the time being that the valve 36 is in normal position the connections of the cylinder 20 with the valve. 36 can thus be disregarded.

If the valve 35 is adjusted into position 35a or 35b for operation of the hydraulic motor 40 in one or the other direction, as the case may be, the cylinder chambers 201 and 202 are supplied through the constant flow valve 43 and the line 42 with part of the pumped oil under pressure via connection 30, inasmuch as these two cylinder chambers communicate through the opening 29. As both faces of the balancing piston 22 are under one and the same pressure, determined by the overflow valve 44, a net pressure transferred to the piston rod 23 will act upon the balancing piston, said net pressure being determined by the difference between the areas of the piston faces, that is to say the area of the piston rod. The hydraulic cylinder 20 will therefore exert a force on the vertically swingable support assembly 11, 14, via the piston rod 23 and the arm 17, said force being determined by the adjusted pressure in the overflow valve 44 and tending to relieve the cylindrical brush 16 of the pressure acting upon it by reason of the. total weight of the support assembly 11, 14, 15 and the cylindrical brush 16. The pressure in the overflow valve 44 can be adapted in such a way that but part of said weight is balanced and a suitable application pressure is obtained for the cylindrical brush 16. Should the brush pass over an elevated portion or enter a depression in the swept surface the balancing piston 22 will immediately take a new position of balance in which the application pressure predetermined by the overflow valve 44 acts upon the cylindrical brush.

The cylinder 20, however, is utilized not only for balancing the sweeping machine but also for raising the cylindrical brush 16. The floating piston 26 is arranged for this purpose. During the balancing function said piston is inoperative and is maintained by the pressure in the cylinder chamber 202 applied against the end wall 20a with the pin 27 projecting toward said end wall. When raising of the brush is to take place the valve 36 is moved to position 36a, the cylinder chambers 201 and 202 being connected with the tank 33 through the line 42, the valve 36 and the line 37, While the pump 32 is connected with the cylinder chamber 203 through the pressure line 34, the valve 36 and the line 45. This cylinder chamber is thus placed under full pressure and urged against one face of the balancing piston 22 with the pin 27 extending toward it, and since the cylinder chamber 201 on the other face of the balancing piston is in communication with the tank 33, the pistons 22 and 26 are it the same time urged upwardly by the pressure pre- Jailing in the system while raising the sweeping machine. For lowering the sweeping machine again the valve 36 is adjusted into position 36b, the communication between the connection 30 and 31, respectively, and the line 34 and 37, respectively, being reversed.

The cylindrical brush 16 will continuously become more light-weight as it is worn, and in the sweeping machine described the balancing force exerted by the cylinder 20 on the support assembly can by simple means be made to follow a predetermined characteristic in dependence on the diameter (weight) of the cylindrical brush. This can be realized for example by mounting the cylinder 20 in such a way that its effective moment arm in respect of the pivot point 12 (said moment arm being the distance between the pivot point 12 and the line extending through the pivot points 18 and 19) varies in a predetermined way in response to the position in which the supporting arms 11 have been adjusted vertically. If the horizontal position illustrated of the supporting arms 11 is the position occupied by these arms with a new unworn brush the supporting arms will incline at a greater or smaller angle downwardly from the pivot point 12 as the cylindrical brush 16 is worn whereby said moment arm become shorter due to the fact that the line extending through pivot points 18 and 19 comes closer to the pivot point 12 when the supporting arms 11 are inclined downwardly from the position shown in FIG. 1. It is also possible to make the overflow valve 44 adjustable in response to the position of the supporting arms 11 so that the predetermined balancing pressure in the cylinder 20 changes according to a predetermined curve. This can be effected for example in the simple manner illustrated in FIG. 1 in which the housing of the overflow valve 44 is secured to the framework 13 and the control means 44a of the valve controlling the overflow pressure is actuated by the supporting arm 11. In such a way the pressure can be automatically adapted to the prevailing operating conditions, and it is possible for example to allow the pressure on the cylindrical brush to rise as the cylindrical brush is worn, which may sometimes be preferable.

The communication between the cylinder chambers 201 and 202 need not be provided through the piston 22 by way of an opening 29 as shown herein, but can also be disposed outside the cylinder 20. In such a case, however, the communication must permit being closed in some way or other when the sweeping machine is to be raised, as the floating piston 26 then will necessarily go past the junction of the connecting line to the cylinder space 202 so that this junction will be located on the pressure side of the floating piston 26, which of course must not be the case.

The valves 35, 36 and 39 are suitably combined into a unit at the drivers seat, as indicated by means of the dashed rectangle in FIG. 3.

Of course, the balancing device described is equally applicable to a sweeping machine mounted forwardly of the draft vehicle as one mounted rearwardly of such vehicle, and is applicable also to a sweeping machine having a rotating vertical broom. The purely structural mechanical details of the support assembly proper can readily be adapted to the prevailing conditions. Therefore, the invention is not limited in any way to the preferred embodiment illustrated, but can be modified within the scope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A sweeping machine comprising a'vehicle, a vertically adjustable support assembly on said vehicle, a cylindrical brush rotatably mounted in said assembly, abutment means on said vehicle, a pressure fluid source, hydraulic jack means connected to said support assembly and said abutment means for partially balancing the weight of said support assembly and said brush, said jack means comprising a hydraulic cylinder and a balancing piston, movable in said hydraulic cylinder and having opposed differential pressure surfaces, a fluid pressure line connectedto said pressure fluid source, means providing fluid communication between said pressure line and said hydraulic cylinder on opposite sides of said balancing piston, and pressure control valve means in said line for supplying said cylinder with fluid from said source at a controlled pressure.

2. A sweeping machine comprising a vehicle, a vertically adjustable support assembly on said vehicle, a cylindrical brush rotatably mounted in said assembly, abutment means on said vehicle, a pressure fluid source, hydraulic jack means connected to said support assembly and said abutment means for partially balancing the weight of said support assembly and said brush, said jack means comprising a hydraulic cylinder, a balancing piston, and a floating piston, said balancing piston being movable in said hydraulic cylinder and having opposed differential pressure surfaces, a fluid pressure line, connected to said pressure fluid source and to said hydraulic cylinder on opposite sides of said balancing piston, pressure control valve means in said line for supplying said cylinder with fluid from said source at a controlled pressure, said floating piston being arranged in said hydraulic cylinder on the side of said balancing piston having the larger pressure surface, and shut-off valve means for connecting said source with said hydraulic cylinder on the side of said floating piston remote from said balancing piston.

3. A sweeping machine comprising a vehicle, a vertically adjustable support assembly on said vehicle, a cylindrical brush rotatably mounted in said assembly, abutment means on said vehicle, a pressure fluid source, hydraulic jack means connected to said support assembly and said abutment means for partially balancing the weight of said support assembly and said brush, said jack means comprising a hydraulic cylinder and a balancing piston, movable in said hydraulic cylinder and having opposed differential pressure surfaces, means defining an opening through said balancing piston for interconnecting the cylinder chambers of said hydraulic cylinder on either side of said balancing piston, a fluid pressure line, connected to said pressure fluid source and to said hydraulic cylinder, and pressure control valve means in said line for supplying said cylinder with fluid from said source at a controlled pressure.

4. A sweeping machine comprising a vehicle, a vertically adjustable support assembly on said vehicle, a cylin drical brush rotatably mounted in said assembly, hydraulic motor means for rotating said brush, abutment means on said vehicle, a pressure fluid source, hydraulic jack means connected to said support assembly and said abutment means for partially balancing the weight of said support assembly and said brush, said jack means comprising a hydraulic cylinder and a balancing piston, movable in said hydraulic cylinder and having opposed differential pressure surfaces, a fluid pressure line, connected to said pressure fluid source and to said hydraulic cylinder on opposite sides of said balancing piston, pressure control valve means in said line for supplying said cylinder with fluid from said source at a controlled pressure, and means connecting said line to the pressure side of said hydraulic motor.

5. A sweeping machine according to claim 4, in which said means connecting said line to the pressure side of said hydraulic motor comprise constant flow valve means.

References Cited UNITED STATES PATENTS 3,037,226 6/1962 Schmidt et :al. 15-82 FOREIGN PATENTS 1,026,771 3/ 1958 Germany.

695,207 8/ 1953 Great Britain.

EDWARD L. ROBERTS, Primary Examiner 

